Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "Give the fixed shares to those entitled to them; whatever remains is for the nearest male."
(b) So he informed us that the one who takes as 'asabah is only a man, except where another Sunnah has made a specific exception; and regarding Aishah's freeing of Barirah, he (peace and blessings be upon him) said: "Wala' belongs only to the one who frees." This hadith shows that she inherits by wala'.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21510